This invention relates to medical devices intended for insertion and extended stay within an anatomical pathway, and more particularly to endotracheal tubes and the like wherein the depth of placement is of particular concern, necessitating prevention and detection of malposition during use.
Endotracheal tubes are widely known and extensively used in emergency, surgical, and critical care settings. Their typical use is as an adjunct in providing adequate respiratory support and airway protection for patients in physically compromised conditions, such as during and following anesthesia or during the course of a serious injury or disease process.
Conventionally, the endotracheal tube comprises an elongated tubular apparatus which includes a centrally located primary passage defined by a cross-sectionally continuous and visually transparent wall. When placed within the intubated pathway, the endotracheal tube has a forward portion and end residing within the trachea, and a rearward portion and end residing a distance outside the intubated pathway, extending through the mouth or nose of the patient. The distance the endotracheal tube is inserted beyond its point of entry within the body of one patient may not be a suitable distance for another patient because of individual anatomical differences or different routes of tube placement; hence, the endotracheal tube is sufficiently elongated to reside at a range of depths within the intubated pathway, and is adjusted to the appropriate depth for the individual requirements of a particular patient. Correct positioning of the endotracheal tube to the appropriate depth of intubation is, therefore, of particular clinical concern.
A circumferentially expansible cuff, in association with an inflation and deflation circuit, is an additional feature common to most varieties of endotracheal tubes and resides in the vicinity of its forward end. During the term of intubation, the cuff is inflated to provide a seal between the endotracheal tube and the tracheal wall, allowing oxygen and other gasses to exchange between the endotracheal tube and the lungs without escaping through the mouth or nose of the patient. Additionally, a radiopaque filament is incorporated within and along the tube wall, and serves to provide for radiographic determination of the endotracheal tube, particularly the forward end thereof, in reference to certain anatomical landmarks.
Of critical importance to patient welfare is a correct placement and positioning of the forward end of the endotracheal tube within the tracheal portion of the intubated pathway. A particular problem, especially during long-term intubation, is the risk and occurrence of unintentional and undetected displacement, and subsequent malposition of the endotracheal tube. It is the common practice to tape the tube in place immediately upon intubation and after an estimation of a correct position of the forward end of the device within the trachea is made. The tube is then readjusted and retaped, if indicated, following radiographic determination and reassessment of its forward end within the trachea. (A distance of 3 to 4 centimeters above the tracheal bifurcation is regarded as safe in preventing the forward end of the endotracheal tube from nearing and entering a mainstem bronchus and in keeping the cuff from contact with the vocal cords.) It is an equally common practice to frequently retape the tube as needed to replace soiled and worn tape, when moving the tube from one side of the mouth to the other side, or when skin integrity is adversely affected by the tape's adhesive surface. At such times, malposition of the endotracheal tube may unintentionally occur. Adding to the displacement and malposition risk is the potential that the patient may pull at the tube and stretch or loosen the tape, or that secretions may adversely act on the tape's adhesive surface, thus allowing displacement of the endotracheal tube to occur.
Problems encountered in the event of endotracheal tube malposition inlude: (1) displacement of the cuff or forward end out of the trachea, resulting in partial or complete tracheal extubation, and (2) disproportionate ventilation of one lung as opposed to the other by the advancement of the forward end of the tube within a mainstem bronchus. Serious sequelae and prolonged and complicated hospitalization may result. In some instances, complications arising from endotracheal tube displacement may be life-threatening. An additional radiograph is often taken to verify correct tube placement, or the need for tube readjustment, each time the position of the endotracheal tube is in question, adding both cost and additional radiation exposure to the list of accompanying problems.
Previously employed methods used to establish and identify on an ongoing basis a correct tube placement have proven unsatisfactory. Ink markings manually placed on the endotracheal tube wall adjacent to its point of entrance within the intubated pathway are either hard to place because of interfering tape, or can be rubbed off, covered, or lifted off when retaping. Wall markings printed on the outer wall surface of the endotracheal tube designating increments of length from a given wall location to the forward end of the tube, sometimes used in indicating and monitoring for a correct depth of placement, are unsatisfactory in that the correct length is often forgotten or otherwise lost to use by other clinicians. A novel, but equally unsatisfactory, method employed to mark the tube consists of placing a suture through the wall of the tube adjacent to its point of entry within the intubated pathway. The suture is then circumferentially wrapped and tied in place around the outside of the tube. This procedure is costly, time consuming, and often interferes with tape replacement. If not carefully placed, the suture may act to prevent a suction catheter or endoscope from passing through the primary passage of the endotracheal tube. All too often, the inconvenience and inadequacies of these and other methods discourage the use of any marking system, underscoring the need for the invention herein described.